Last 11 August China banned the imports of pork and pork products from six processing plants and six cold storage facilities in the United States due to concerns related to the use of ractopamine.
Since the last 1 July 2014 China requires an export cerficate declaring that the pork shipped to China is free of ractopamine.
Monday August 11, 2014. USA
http://www.fsis.usda.gov
Wednesday August 13, 2014. China
http://www.gw.com.cn